In Bales, et al. U.S. patent application Ser. No. 806,526, filed Dec. 9, 1985, now abandoned a hemostasis valve which is improved over other prior art versions is disclosed. Hemostasis valves are currently on catheters for performing percutaneous transluminal coronary angioplasty (PTCA), as well as angiographic procedures, for example, where x-ray contrast fluid is inserted into the coronary artery.
In PTCA, stenotic regions of coronary blood vessels are dilated by advancing a dilatation catheter through blood vessels into the stenotic region. The dilatation catheter advances over a guide wire, which guide wire moves forward, followed by the catheter, followed by another advance of the guide wire, etc. The guide wire-dilatation catheter system may be introduced through a guiding catheter to facilitate its placement.
To prevent the leakage of blood out of the proximal end of the catheter, a hemostasis valve is provided at the proximal end, to prevent seepage of blood between the guide wire and the catheter. Besides the design shown in the above-cited patent application, numerous other types of hemostasis valves are known. See for example Stevens, U.S. Pat. No. 4,000,739. Another design of hemostasis valve is the Tuohy-Borst type, making use of an adjustable, compressive sleeve which is axially compressed about the guide wire that it seals by means of a two-piece, screw threaded housing. Other designs may use an "O" ring and a tapered seat instead of a sleeve.
Many designs require tightening of the valve when high pressure X-ray contrast fluid or the like is run through the catheter. However, with such high pressure sealing, the guide wire cannot be advanced in effective manner, so the valve, such as a Tuohy-borst valve, must be loosened so that the operator can "feel" any resistance encountered by the forward advancement of the guide wire, during the operation of advancing the guide wire through blood vessels.
The degree of loosening of the valve can be critical. If excessively loosened, low pressure leakage may occur. If loosened too little, the guide wire cannot be effectively advance. Accordingly, it turns out that for the most effective performance of PTCA and angiography procedures, a hemostasis valve which is highly controllable is needed, so that the guide wire can be easily advanced, while low pressure leakage is prevented on an easy, reliable basis, without the need for great skill and experience in operation of the valve.
Thus a hemostasis valve should be provided with reliable sealing against low pressure leakage around a guide wire or the like. At the same time, an adjustable seal should also be provided which may be adjusted to seal against high pressures. Accordingly, the adjustable seal may be applied or released as desired, but, preferably, at least a low pressure seal may be constantly present to stop leakage upon release of the high pressure seal. Thus, manipulation of the high pressure seal is less critical, and requires less skill in order to avoid leakage.
Also, the surgeon who is manipulating a typical catheter for entering coronary blood vessels, for example, is overburdened with respect to things to hold and manipulate during this process. The hemostasis valve described above provides improved efficiency of adjustment of the adjustable valve, to relieve the burden on the surgeon.
While the invention of the cited patent application Ser. No. 806,526 provides improved efficiency of adjustment, it does so by the addition of a second sealing site, spaced from a first adjustable, compressible sleeve valve which is provided to give the variable pressure sealing. It is of course a complexity of manufacture to provide a second sealing site, requiring a second sleeve or gasket.
By this invention, improved efficiency of adjustment of the hemostasis valve of this invention can be provided through the use of a single, compressible tubular sleeve or gasket. In this gasket, high pressure sealing may be applied, or released, to alternatively permit the application of high pressure x-ray contrast fluid or the like, and also to permit advancement of catheters and guide wires without blood leakage through the application of a low pressure seal which remains, even when the high pressure seal is released. Despite this, the advantage remains that only a single resilient, tubular gasket is present to provide both of these functions.
Additionally by this invention, an improved structure for application and release of the adjustable, high pressurizable seal is provided.